4. A study to assess the capability of subsurface ow wetland systems to remove biochemical oxygen demand

(BOD) and various other chemical constituents resulted in the accompanying data on x  BOD mass loading (kg/ha/d) and y  BOD mass removal

(kg/ha/d) ( Subsurface Flow Wetlands A Performance Evaluation, Water Environ. Res., 1995:

244—247).

x 3 8 10 11 13 16 27 30 35 37 38 44 103 142 y 4 7 8 8 10 11 16 26 21 9 31 30 75 90

a. Construct boxplots of both mass loading and mass removal, and comment on any interesting features.

b. Construct a scatter plot of the data, and comment on any interesting features.